/*
Flot plugin that adds some extra symbols for plotting points.

The symbols are accessed as strings through the standard symbol
choice:

  series: {
		points: {
			symbol: "square" // or "diamond", "triangle", "cross"
		}
  }

*/

(function ($) {
	function processRawData(plot, series, datapoints) {
		// we normalize the area of each symbol so it is approximately the
		// same as a circle of the given radius

		var handlers = {
			square: function (ctx, x, y, radius, shadow) {
				// pi * r^2 = (2s)^2  =>  s = r * sqrt(pi)/2
				var size = radius * Math.sqrt(Math.PI) / 2;
				ctx.rect(x - size, y - size, size + size, size + size);
			},
			diamond: function (ctx, x, y, radius, shadow) {
				// pi * r^2 = 2s^2  =>  s = r * sqrt(pi/2)
				var size = radius * Math.sqrt(Math.PI / 2);
				ctx.moveTo(x - size, y);
				ctx.lineTo(x, y - size);
				ctx.lineTo(x + size, y);
				ctx.lineTo(x, y + size);
				ctx.lineTo(x - size, y);
			},
			triangle: function (ctx, x, y, radius, shadow) {
				// pi * r^2 = 1/2 * s^2 * sin (pi / 3)  =>  s = r * sqrt(2 * pi / sin(pi / 3))
				var size = radius * Math.sqrt(2 * Math.PI / Math.sin(Math.PI / 3));
				var height = size * Math.sin(Math.PI / 3);
				ctx.moveTo(x - size/2, y + height/2);
				ctx.lineTo(x + size/2, y + height/2);
				if (!shadow) {
					ctx.lineTo(x, y - height/2);
					ctx.lineTo(x - size/2, y + height/2);
				}
			},
			cross: function (ctx, x, y, radius, shadow) {
				// pi * r^2 = (2s)^2  =>  s = r * sqrt(pi)/2
				var size = radius * Math.sqrt(Math.PI) / 2;
				ctx.moveTo(x - size, y - size);
				ctx.lineTo(x + size, y + size);
				ctx.moveTo(x - size, y + size);
				ctx.lineTo(x + size, y - size);
			}
		}

		var s = series.points.symbol;
		if (handlers[s])
			series.points.symbol = handlers[s];
	}
	function init(plot) {
		plot.hooks.processDatapoints.push(processRawData);
	}
	$.plot.plugins.push({
		init: init,
		name: 'symbols',
		version: '1.0'
	});
})(jQuery);
